The present invention generally relates to wireless communication systems, specifically, to data transmission synchronization between a baseband unit and a remote radio head of a wireless communication system base station in wireless access network.
The latest generations of wireless communication systems use remote radio head (RRH) technology in a distributed base station architecture where all radio related functions are included in a Remote Radio Head which can be installed next to the antenna and which allows for greater distances between the RRH and antenna of a base station (BS) and the baseband unit (BBU) of the BS, reducing set-up and operational costs. The BS can centralize multiple BBUs and deploy the RRHs and the antennae in a distributed manner. FIG. 1 shows an architecture supporting dynamic RRH stream-switching for different BBU boards, wherein a plurality of BBU boards serve as a resource pool to provide processing resources for RRHs in an on-demand manner.
In digital communication network, reliably transmitting audio, video and data requires accurate timing and synchronization. In traditional implementation of communication between a BBU and a RRH, the BBU and RRH of a base station are connected directly through a TDM (time division multiplexing) link, on which data is transmitted at clock of the TDM link, and thus transmission time-delay is generally fixed and transmission jitter is not generated. Furthermore, processing time-delay is also generally fixed due to the use of computing platforms based on DSP/FPGA, (Digital Signal Processing/Field Programmable Gate Arrays) etc., which do not have operating system.
Next generation wireless access network architecture commonly adopts time division duplex (TDD) wireless communication system, for which data transmission between a BBU and a RRH is based on a packet switching network, such as Ethernet or Infiniband, and switch, and thereby data transmission time-delay is generally not fixed and transmission jitter may occur. Due to the use of computing and transmitting resource pool based on open IT architecture, processing time-delay is not fixed under the influence of operation system (e.g. task scheduling, etc.).